Thanks for the great info.
One question, though. How do you make 22-250 cases from .243? Who makes the case forming dies for that operation.
Right now I've done the following case prep and accuracy steps:
1.) Trimmed all the cases to the midpoint between the trim to and max case length (1.907"), to ensure uniform case length and square the mouths. Camfered and deburred the mouths.
2.) De-burred the flash holes.
3.) Uniformed the primer pockets.
4.) After finishing all of the case prep steps that involved removal of material, I then weighed and separated the brass into +/- 0.5gr lots, discarding any cases that were more than 2 grains from the mean weight. I then chose 50 cases from the group of cases closest to the mean, and set aside the other groups to be used when these cases wear out.
5.) Neck sized only. Actually, this step was done before trimming, but I just thought about it now and didn't want to change the step numbers!
6.) Adjusted the seating depth to approx .015" from the lands by using the sooted bullet method. My next step will be to get a Stoney Pt. OAL gauge and refine the seating depth further, but for safety and lack of a more accurate measuring method, I decided that .015" was as close as I'll get for now.
7.) When seating the bullets I use a three step proceedure where I start the bullet about 1/3 into the case, turn the case about 120 degrees, seat another 1/3, turn 120 degrees, finish seating. I read in one of my manuals that doing this tends to minimize bullet runout. I don't yet have a method to check it, but I thought I'd do it anyway as it should hurt anything either.
8.) Weighed all powder charges as precisely as possible. Time-consuming but worth it. I found that my RCBS uniflow powder measure will throw charges to about +/- 0.1gr, but with the scale and powder trickler I am probably getting the charges within +/- 0.02gr or closer.
The next tool purchases will be a Stoney Pt. OAL gauge and bullet comparator to really dial in the seating depth, and an outside neck turner attachment for my Forster trimmer. I think that neck turning will have a big impact on accuracy, as I can visually see slight variations in neck thickness.
I've already done the gross tuning of the charges by starting at the minimum and working up in the steps of about 1gr as posted my manual. I found that best accuracy was at the min. charge and at near the max charge, with the group opening up in between (is that normal?). When I shot the first handloads I had intended to chrony them, but I was having one of those days and while I remembered to pack my chrony in my shooting bag, I forgot to put the tripod in the truck! So no chrony'd loads from the last batch. The last batch I handloaded I decided to further refine the powder charge, so I loaded the 50 rounds starting at 33.8gr Varget and moved up in 0.2gr increments back to the published max load of 34.6gr. Since I'm new to handloading, I'm not going to go over the published max charge, even though the cases showed no pressure signs at the max load. I'm going for accuracy and not speed anyway, and I don't feel like dancing with the devil on this. I watched another guy suffer a ruptured case that blew the magazine and floorplate right out of his rifle, and I don't want that to be me if I can help it. [8D]
Thanks for all the great advice, guys. Please keep it coming. Now that I've tried it I find handloading absolutely fascinating, and your advice is a big help!